The present invention relates to liquid filtration systems, and in particular to spin-on types of filter elements and filter heads therefor.
Vehicles powered by liquid petroleum fuels, such as diesel fuel or gasoline, have fuel systems that typically include fuel filters. The fuel filter operates to minimize the risk that contaminates, such as dirt particles or water, will reach other components of the system where the contaminates may cause damage.
There are many types of fuel filters known in the prior art. Some provide only particulate filtration. Others provide filtration and water separation. A popular configuration for fuel filters for larger vehicles includes a stationary head which is connected in the fuel line of the vehicle fuel system. A replaceable element attaches to the head, usually in xe2x80x9cspin-onxe2x80x9d fashion. The element may be replaced periodically to prevent the element from being clogged by contaminates.
One problem with such spin-on elements is that when a filter element is removed from the filter head, any fuel remaining in the head can drain out of the head onto the operator, the surrounding engine, and/or the ground. This is undesirable from a clean-up and environmental standpoint. Air can also enter the head and pass downstream to the remainder of the fuel system. This can cause rough operation of the engine during start-up, as well as damage downstream components.
Another problem is that filter elements with different efficiencies, applications, and/or qualities can sometimes fit on the same filter head. It is important to replace a spent element with the same or a similar type of element to ensure proper filtration of the fuel. It is also important to run the engine with an element installed. Failing to install an element can also allow damage to occur to downstream components.
Certain elements have been designed whereby the element can only fit a certain filter head, and where the filter will not operate without such a filter element installed. Clausen, U.S. Pat. No. 5,643,446, for example, shows and describes a valve in the filter head which is actuated by an elongated projection on the filter element. The projection extends upwardly from one of the end caps on the element, and pushes the valve element upwardly (inwardly) into the filter head when the element is attached to the head. The valve generally remains closed if an incorrect element (without such a projection) is installed, or if no element is present. The valve also prevents fuel from draining out of the filter head when the element is replaced, and prevents air entering the filter head.
While the Clausen filter has been useful in many lower-pressure applications, the valve in the filter head may open in higher pressure applications. This is because the fuel pressure can urge the spring-biased valve inwardly into the head when the pressure increases above the cracking force of the spring. Strong springs and robust valve elements have therefore been used to keep the valve in a closed position. However, it can be more difficult to assemble the filter element on the filter head with such stronger springs. The strong springs and robust valve elements also add cost and complexity to the filter head--as well as to the filter element, as the projection on the filter element must be strengthened. Even with all these precautions, the undesirable opening of the valve may still occur in some high pressure situations.
It is therefore believed that there is still a need for a simple, compact, easy-to-assemble, spin-on filter element and filter head, where the filter element can only be used with a specific filter head, and where the filter will not operate without such a filter element installed. It is also believed there is a demand for a filter where the filter head prevents fuel draining out of the head, and air entering the head, when the filter element is removed.
The present invention provides a novel and unique spin-on type of filter element and filter head therefor. Fuel is prevented from draining out of the filter head and air is prevented from entering the head, when an element is removed. The filter head can also only be used with a specific filter element, and the filter will not operate without such a filter element installed.
According to the present invention, the filter head has inlet and outlet ports. An annular inlet chamber is provided in the base of the head, and is fluidly connected to the inlet port. A threaded nipple is centrally located and projects axially away from the base. The nipple includes an internal flow passage fluidly connected to the outlet port. A valve assembly including elongated, spring-biased valve member is located in the flow passage of the nipple. The valve member is normally biased upwardly into a closed positionxe2x80x94preventing flow through the passage. A portion of the valve member projects outwardly from the nipple. The outwardly-projecting portion includes a series of threads.
The filter element of the present invention includes a cylindrical housing enclosing a ring-shaped filter media. The housing preferably includes an open first end, and a second end. The second end can be closed, or can be open and include means to allow attachment of a collection bowl. End caps are provided at each end of the filter media, with an annular portion of each end cap fixed (e.g., adhesively bonded) to the respective end of the media. A tap plate encloses the filter element in the housing, and is secured to the open end of the housing. The tap plate includes a central threaded opening, and a series of peripheral openings spaced radially outward from the central opening. The central tap plate opening cooperates with the threaded nipple on the filter head to allow the filter element to be screwed on (spun-on) to the filter head. The peripheral openings are located for receiving fuel from the inlet chamber of the filter head when the element is attached to the filter head.
The filter element supports a threaded sleeve internally of the element, co-axially aligned with the central opening in the tap plate. The threaded sleeve cooperates with the threaded valve member of the filter head when the filter element is screwed onto the head to cause the valve member to move to an open position. The thread pitch (angle) on the valve member/sleeve combination is preferably greater than the thread pitch of the nipple/tap plate combination, which causes the valve member to be pulled or drawn axially outward from the nipple as the filter element is threaded onto the filter head, allowing flow through the nipple. The threaded sleeve can be supported on a radial end wall at the internal end of an annular wall extending axially inward into the media from the upper end cap, or by other means that rigidly supports the sleeve centrally in the filter element. Fluid can pass through the openings in the radial end wall the radial supports to the central passage in the nipple and then to the outlet in the filter head when the filter element is installed. The threaded sleeve, radial end wall and annular internal wall are preferably formed integrally (and more preferably, unitarily) with the annular portion of the end cap.
As described above, the screwing of the filter element onto the filter head causes the valve member to move to an open position. This enables fuel to flow out of the filter element to the outlet of the filter head. Disengagement of the filter element allows the valve member to move to a closed position. This prevents air entering the head and passing downstream to the remainder of the fuel system when the element is removed. This also prevents fuel draining out of the head during an element change.
The threaded sleeve on the filter element is sized and configured so that only a sleeve having a certain length, diameter, and thread pitch will properly engage the threads on the valve member to draw the valve member to an open position. The sleeve may have different configurations with various elements, each of which corresponds to a particular filter head. Further, the valve assembly is constructed such that if an improper element is installed, fuel normally forces the valve member into a closed position, which prevents the valve element from opening during high pressure situations. As a result, only a proper filter element will operate in conjunction with the filter head, and the filter head will not operate without a proper filter element installed.
Further features of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings.